docs: def node_val_dump(self):
          """Yield the entire contents of the node_val table."""
          self._flush_node_val()
          for (
                  graph, node, key, branch, turn, tick, value
          ) in self.sql('node_val_dump'):
              yield (
                  self.unpack(graph),
                  self.unpack(node),
                  self.unpack(key),
                  branch,
                  turn,
                  tick,
                  self.unpack(value)
              )